Improvements in and relating to grass cutting machines

Abstract: This invention relates to a grass cutting machine which comprises a chassis, a cutting member, a power source, a drive line for drivingly connecting the power source and the cutting member, means for creating a stream (16,304) of pressure air, a grass collection device (100,316), means for removably supporting the collection device on the machine, the collection device comprising a receptacle (318) for receiving cut grass, the receptacle having at least one inlet (15,315) for entry of cut grass entrained in a stream of air from said source and including a base wall (10), an upper wall (11) and one or more side walls (12), a part of at least one of the base and side walls including an air permeable region to retain cut grass in the receptacle and to permit the said stream of air to be drawn by said source through cut grass retained in the receptacle and through each air permeable region thereby serving, in use, to filter the air stream and compact the cut grass in the receptacle.

Description: This invention relates to grass cutting machines and particularly to means for effectively collecting cut grass produced by such machines. Grass cutting machines can be divided into two major categories, namely, those in which grass is cut using a multi-bladed cylindrical cutter with its axis of symmetry mounted for rotation about a substantially horizontal axis - the so called cylinder mower - and those in which a cutting member is mounted for rotation about a vertical axis and cutting is performed in a substantially horizontal plane - the so called hover mower which may also be supported on wheels and/or rollers in which case they are referred to as wheeled/rotary mowers. A form of combined mower has been proposed in which a mower having a cylindrical cutter is at least partially supported on a cushion of air. Such a combined mower is described in our prior US Patent No. 4, 738, 086. Our prior European Patent 0204573 corresponds to US 4738086, and discloses a lawnmower having a cylinder type cutter blade arrangement, but which is supported not by wheels, but by cushion of pressurized air. An air pump is disposed at the very rear of the lawnmower, which draws air from a grass box which is located above the deck or chassis of the mower. The grass box includes a forwardly sloping, air-permeable filter through which the air pump draws air from the grass box. The air pump then supplies air under pressure beneath the chassis in order to generate the cushion of air. The cylindrical cutter blades cut the grass, and throw the grass cuttings into the grass box, the passage of which is enhanced by the flow of air into the receptacle past the cutter blades. Conventionally, grass cut by cylinder mowers is thrown into a grass box by virtue of a force applied to the cuttings due to rotation of the cylindrical cutter. In the case of rotary mowers, cut grass may be forced into a grass collector directly by action of the rotating cutting member which may or may not be formed with auxiliary fins for forming an air stream during cutting. Alternatively, or in addition, the air stream may be produced by an impeller. In either case cut grass is entrained in the stream of air and transported into a grassbox. The position of cut grass in a grass collector fitted to any of the above types of mower is effected quantitatively, that is, by the effect of the forces transporting the cut grass and, as these forces diminish, the weight of the grass cuttings per se causes deposition thereof in the grass box. It is an aim of the present invention to improve the grass collecting capabilities of the various grass cutting machines mentioned above by compacting cuttings collected in the grass box. The present invention provides an air supported grass cutting machine which, in use, is supported solely by pressure air, the machine comprising a chassis, a cutting member, a power source, a drive line for drivingly connecting the power source and the cutting member, air impelling means for creating a stream of air, a grass collection device including a receptacle for receiving cut grass, and means for removably supporting the receptacle on the chassis, the receptacle having an inlet for entry of cut grass entrained in the said stream of air being led towards said air impelling means, and including a base wall, an upper wall and one or more side walls, a part of at least the base wall including an air-permeable region through which the said stream of air is drawn by the air impelling means to retain cut grass in the receptacle and to permit the said stream of air to be drawn through cut grass retained in the receptacle and through the air-permeable region thereby serving, in use, to filter the said stream of air and compact the cut grass in the receptacle, the receptacle being mounted on the chassis, and the air-permeable region being disposed relative to the centre of gravity of the machine so that the said stream of air leading to the air impelling means passes through the air-permeable region in such a manner that cut grass retained in the receptacle is collected substantially in the region of the centre of the gravity of the machine. The invention will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic longitudinal cross-section of a conventional hover mower in which cut grass is quantitatively deposited in a grass collector; and Figure 2 is a cross-section similar to Figure 1 according to the present invention. Figure 1 shows a conventional hover-mower, where grass cuttings are drawn into a collection box 1 in a main airstream and, subsequently, "fall out" of the flow of air, into the box, with nothing more than the force of gravity compacting the grass clippings. The conventional hover-mower of Figure 1 has a chassis 2 (sometimes referred to in the art, as a hood), a motor 3 which may be an electric motor or an internal combustion engine. The motor has an output drive shaft 4 on which an impeller 5 and a cutting member 6 are coaxially mounted. The grass collection box 1 is removably mounted on the chassis and a filter 1A serves, in use, to separate grass cuttings G from the main air stream as indicated by arrows 5 produced by the impeller to effect both hover and grass collection, the grass-cuttings entering the collection box through inlet 1B. Referring to Figure 2 the main air stream passes, in use, under suction through the grass cuttings in the collection box thereby compacting the clippings as the box fills up. This method of grass collection results in more grass cuttings being collected in the same volume of the collection box of the embodiment of Figure 1. A grass collection box 100 is mounted on a chassis 14 and includes a receptacle removably supported therein and indicated by dotted lines. The receptacle has a base 10, upper 11 and side walls 12 made wholly from or containing regions which are permeable to air. A plenum chamber 13 is disposed between the base 10 and the chassis 14. In operation a stream of air is created by an impeller member 16 which is coaxially mounted with a cutting member 19 and is indirectly driven by a motor 17 via a belt 18. The stream of air follows a clockwise motion indicated by arrows T and entrains grass cuttings which are led into the collection box 100 via inlet 15. The suction effect caused by operation of the impeller draws the entrained grass cuttings into the grass box to compact them on the air permeable base wall 10. Thus air from the air stream is filtered as it passes through the compacted cuttings. An advantage of the present invention is that grass cuttings are compacted in the region of the centre of gravity of the machine thereby serving to keep the machine substantially parallel to the grass being cut and producing a relatively even cut.

Claims: An air supported grass cutting machine which, in use, is supported solely by pressure air, the machine comprising a chassis (14), a cutting member (19), a power source (17), a drive line (18) for drivingly connecting the power source (17) and the cutting member (19), air impelling means (16) for creating a stream of air, a grass collection device including a receptacle for receiving cut grass, and means for removably supporting the receptacle on the chassis (14), the receptacle having an inlet (15) for entry of cut grass entrained in the said stream of air being led towards said air impelling means (16), and including a base wall (10), an upper wall (11) and one or more side walls (12), a part of at least the base wall (10) including an air-permeable region through which the said stream of air is drawn by the air impelling means (16) to retain cut grass in the receptacle and to permit the said stream of air to be drawn through cut grass retained in the receptacle and through the air-permeable region thereby serving, in use, to filter the said stream of air and compact the cut grass in the receptacle, the receptacle being mounted on the chassis (14), and the air-permeable region being disposed relative to the centre of gravity of the machine so that the said stream of air leading to the air impelling means (16) passes through the air-permeable region in such a manner that cut grass retained in the receptacle is collected substantially in the region of the centre of the gravity of the machine. A machine according to claim 1, wherein the power source (17) drives the cutting member (19) and the air impelling means (16) indirectly through a belt (18), thereby permitting the collection device to be mounted generally above the air impelling means (16). A machine according to claim 1 or 2, wherein at least one side wall (12) includes an air permeable region. A machine according to any one of claims 1 to 3, wherein the base wall (10) including an air permeable region constitutes a supporting member for the cut grass retained in the receptacle and wherein the supporting member is disposed in spatial relationship relative to the said air impelling means (16) to form an air chamber (13) therebetween. A machine according to any one of the preceding claims, wherein the cutting member (19) is a cutting blade mounted for rotation in a substantially horizontal plane within a cutting chamber. A machine according to claim 5, wherein the air impelling means (16) is an impeller mounted for coaxial rotation with the cutting blade (19). A machine according to claim 6, wherein the drive line is an output shaft from the power source (17) with the impeller (16) and the cutting blade (19) mounted for coaxial rotation with the output shaft. A machine according to any one of claims 5 to 7, wherein the inlet (15) for entry of cut grass is disposed externally of the cutting chamber. A machine according to any one of claims 5 to 7, including a duct connecting the inlet (15) for entry of cut grass and the cutting chamber. A machine according to any one of claims 5 to 7, wherein the inlet (15) for entry of cut grass is disposed externally of the chassis (14). A machine according to any one of the preceding claims, including a duct extending into the receptacle from the inlet (15). A machine according to claim 1, wherein the receptacle is supported within an outer casing. A machine according to any one of the preceding claims, wherein the base wall (10) and each side wall (12) is air permeable. A machine according to any one of the preceding claims, wherein the collection device further includes an outer housing within which the receptacle is removably mounted with at least the base wall (10) disposed in spaced relationship with the collection device, the said spatial relationship affording communication between the interior of the receptacle and the air impelling means (16) via the air permeable region.

Inventors: DUNN KEN, DUNN, KEN
Applicants: ELECTROLUX OUTDOOR PROD LTD, ELECTROLUX OUTDOOR PRODUCTS LIMITED
Application year: 1994
Main classification: A01D34
IPC codes: A01D34, A01D43